System and method for operating an air conditioner unit

ABSTRACT

An air conditioner unit includes a variable speed compressor for circulating refrigerant through an outdoor heat exchanger and an indoor heat exchanger, an indoor fan, and an outdoor fan. A controller obtains an indoor temperature using an indoor temperature sensor and operates the variable speed compressor, the indoor fan, and the outdoor fan at a first capacity level to adjust the indoor temperature toward a target temperature. The controller determines that a rate of change of the indoor temperature is below a predetermined rate threshold and operates the variable speed compressor, the indoor fan, and the outdoor fan at a second capacity level.

FIELD OF THE INVENTION

The present disclosure relates generally to air conditioner units, and more particularly to methods of operating an air conditioner unit at improved efficiency and while making less noise.

BACKGROUND OF THE INVENTION

Air conditioner or conditioning units are conventionally utilized to adjust the temperature indoors—i.e., within structures such as dwellings and office buildings. Such units commonly include a closed refrigeration loop to heat or cool the indoor air. Typically, the indoor air is recirculated while being heated or cooled. A variety of sizes and configurations are available for such air conditioner units. For example, some units may have one portion installed within the indoors that is connected, by e.g., tubing carrying the refrigerant, to another portion located outdoors. These types of units are typically used for conditioning the air in larger spaces.

Another type of unit, sometimes referred to as a packaged terminal air conditioner unit (PTAC), may be used for somewhat smaller indoor spaces that are to be air conditioned. These units may include both an indoor portion and an outdoor portion separated by a bulkhead and may be installed in windows or positioned within an opening of an exterior wall of a building. When a conventional PTAC is operating in a cooling or heating mode, a single speed compressor circulates refrigerant within a sealed system, while indoor and outdoor fans urges flows of air across indoor and outdoor heat exchangers respectively.

Typical control algorithms for conventional PTACs (and other air conditioner units) maintain the room temperature around the target temperature by cycling the compressor, the indoor fan, and the outdoor fan on and off as the measured temperature cycles inside and outside a range surrounding the target temperature. However, the single speed of operation of the compressor and fans generates a lot of noise and operates outside of the ideal operating points of these components, resulting in poor unit efficiency.

Accordingly, improved air conditioner units and methods of operation to achieve a target temperature would be useful. More specifically, a packaged terminal air conditioner unit that regulates the indoor temperature to the target temperature while reducing noise and improving unit efficiency would be particularly beneficial.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.

In one exemplary embodiment, an air conditioner unit is provided including a refrigeration loop including an outdoor heat exchanger and an indoor heat exchanger, a variable speed compressor operably coupled to the refrigeration loop and being configured for urging a flow of refrigerant through the outdoor heat exchanger and the indoor heat exchanger, an indoor fan configured for urging a flow of indoor air through the indoor heat exchanger, an outdoor fan configured for urging a flow of outdoor air through the outdoor heat exchanger, an indoor temperature sensor, and a controller operably coupled to the variable speed compressor, the indoor fan, the outdoor fan, and the indoor temperature sensor. The controller is configured to obtain an indoor temperature using the indoor temperature sensor, operate the variable speed compressor, the indoor fan, and the outdoor fan at a first capacity level to adjust the indoor temperature, determine that a rate of change of the indoor temperature is below a predetermined rate threshold, and operate the variable speed compressor, the indoor fan, and the outdoor fan at a second capacity level.

In another exemplary embodiment, a method of operating an air conditioner unit, the air conditioning unit including a refrigeration loop, a variable speed compressor, an indoor fan, an outdoor fan, and an indoor temperature sensor. The method includes obtaining an indoor temperature using the indoor temperature sensor, operating the variable speed compressor, the indoor fan, and the outdoor fan at a first capacity level to adjust the indoor temperature, determining that a rate of change of the indoor temperature is below a predetermined rate threshold, and operating the variable speed compressor, the indoor fan, and the outdoor fan at a second capacity level.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

FIG. 1 provides a perspective view of an air conditioner unit, with part of an indoor portion exploded from a remainder of the air conditioner unit for illustrative purposes, in accordance with one exemplary embodiment of the present disclosure.

FIG. 2 is another perspective view of components of the indoor portion of the exemplary air conditioner unit of FIG. 1.

FIG. 3 is a schematic view of a refrigeration loop in accordance with one embodiment of the present disclosure.

FIG. 4 is a rear perspective view of an outdoor portion of the exemplary air conditioner unit of FIG. 1, illustrating a vent aperture in a bulkhead in accordance with one embodiment of the present disclosure.

FIG. 5 is a front perspective view of the exemplary bulkhead of FIG. 4 with a vent door illustrated in the open position in accordance with one embodiment of the present disclosure.

FIG. 6 is a rear perspective view of the exemplary air conditioner unit and bulkhead of FIG. 4 including a fan assembly for providing make-up air in accordance with one embodiment of the present disclosure.

FIG. 7 is a side cross sectional view of the exemplary air conditioner unit of FIG. 1.

FIG. 8 illustrates a method for controlling a packaged terminal air conditioner unit in accordance with one embodiment of the present disclosure.

FIG. 9 illustrates a flow diagram illustrating an exemplary process for operating an air conditioner having a variable speed compressor and fans according to an exemplary embodiment of the present subject matter.

Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

Referring now to FIGS. 1 and 2, an air conditioner unit 10 is provided. The air conditioner unit 10 is a one-unit type air conditioner, also conventionally referred to as a room air conditioner or a packaged terminal air conditioner (PTAC). The unit 10 includes an indoor portion 12 and an outdoor portion 14, and generally defines a vertical direction V, a lateral direction L, and a transverse direction T. Each direction V, L, T is perpendicular to each other, such that an orthogonal coordinate system is generally defined.

A housing 20 of the unit 10 may contain various other components of the unit 10. Housing 20 may include, for example, a rear grill 22 and a room front 24 which may be spaced apart along the transverse direction T by a wall sleeve 26. The rear grill 22 may be part of the outdoor portion 14, and the room front 24 may be part of the indoor portion 12. Components of the outdoor portion 14, such as an outdoor heat exchanger 30, an outdoor fan 32, and a compressor 34 may be housed within the wall sleeve 26. A fan shroud 36 may additionally enclose outdoor fan 32, as shown.

Indoor portion 12 may include, for example, an indoor heat exchanger 40, a blower fan or indoor fan 42, and a heating unit 44. These components may, for example, be housed behind the room front 24. Additionally, a bulkhead 46 may generally support and/or house various other components or portions thereof of the indoor portion 12, such as indoor fan 42 and the heating unit 44. Bulkhead 46 may generally separate and define the indoor portion 12 and outdoor portion 14.

Outdoor and indoor heat exchangers 30, 40 may be components of a refrigeration loop 48, which is shown schematically in FIG. 3. Refrigeration loop 48 may, for example, further include compressor 34 and an expansion device 50. As illustrated, compressor 34 and expansion device 50 may be in fluid communication with outdoor heat exchanger 30 and indoor heat exchanger 40 to flow refrigerant therethrough as is generally understood. More particularly, refrigeration loop 48 may include various lines for flowing refrigerant between the various components of refrigeration loop 48, thus providing the fluid communication there between. Refrigerant may thus flow through such lines from indoor heat exchanger 40 to compressor 34, from compressor 34 to outdoor heat exchanger 30, from outdoor heat exchanger 30 to expansion device 50, and from expansion device 50 to indoor heat exchanger 40. The refrigerant may generally undergo phase changes associated with a refrigeration cycle as it flows to and through these various components, as is generally understood. Suitable refrigerants for use in refrigeration loop 48 may include pentafluoroethane, difluoromethane, or a mixture such as R410a, although it should be understood that the present disclosure is not limited to such examples and rather that any suitable refrigerant may be utilized.

As is understood in the art, refrigeration loop 48 may be alternately operated as a refrigeration assembly (and thus perform a refrigeration cycle) or a heat pump (and thus perform a heat pump cycle). As shown in FIG. 3, when refrigeration loop 48 is operating in a cooling mode and thus performs a refrigeration cycle, the indoor heat exchanger 40 acts as an evaporator and the outdoor heat exchanger 30 acts as a condenser. Alternatively, when the assembly is operating in a heating mode and thus performs a heat pump cycle, the indoor heat exchanger 40 acts as a condenser and the outdoor heat exchanger 30 acts as an evaporator. The outdoor and indoor heat exchangers 30, 40 may each include coils through which a refrigerant may flow for heat exchange purposes, as is generally understood.

According to an example embodiment, compressor 34 may be a variable speed compressor. In this regard, compressor 34 may be operated at various speeds depending on the current air conditioning needs of the room and the demand from refrigeration loop 48. For example, according to an exemplary embodiment, compressor 34 may be configured to operate at any speed between a minimum speed, e.g., 1500 revolutions per minute (RPM), to a maximum rated speed, e.g., 3500 RPM. Notably, use of variable speed compressor 34 enables efficient operation of refrigeration loop 48 (and thus air conditioner unit 10), minimizes unnecessary noise when compressor 34 does not need to operate at full speed, and ensures a comfortable environment within the room.

Specifically, according to an exemplary embodiment, compressor 34 may be an inverter compressor. In this regard, compressor 34 may include a power inverter, power electronic devices, rectifiers, or other control electronics suitable for converting an alternating current (AC) power input into a direct current (DC) power supply for the compressor. The inverter electronics may regulate the DC power output to any suitable DC voltage that corresponds to a specific operating speed of compressor. In this manner compressor 34 may be regulated to any suitable operating speed, e.g., from 0% to 100% of the full rated power and/or speed of the compressor. This may facilitate precise compressor operation at the desired operating power and speed, thus meeting system needs while maximizing efficiency and minimizing unnecessary system cycling, energy usage, and noise.

In exemplary embodiments as illustrated, expansion device 50 may be disposed in the outdoor portion 14 between the indoor heat exchanger 40 and the outdoor heat exchanger 30. According to the exemplary embodiment, expansion device 50 may be an electronic expansion valve that enables controlled expansion of refrigerant, as is known in the art. More specifically, electronic expansion device 50 may be configured to precisely control the expansion of the refrigerant to maintain, for example, a desired temperature differential of the refrigerant across the indoor heat exchanger 40. In other words, electronic expansion device 50 throttles the flow of refrigerant based on the reaction of the temperature differential across indoor heat exchanger 40 or the amount of superheat temperature differential, thereby ensuring that the refrigerant is in the gaseous state entering compressor 34. According to alternative embodiments, expansion device 50 may be a capillary tube or another suitable expansion device configured for use in a thermodynamic cycle.

According to the illustrated exemplary embodiment, outdoor fan 32 is an axial fan and indoor fan 42 is a centrifugal fan. However, it should be appreciated that according to alternative embodiments, outdoor fan 32 and indoor fan 42 may be any suitable fan type. In addition, according to an exemplary embodiment, outdoor fan 32 and indoor fan 42 are variable speed fans, e.g., similar to variable speed compressor 34. For example, outdoor fan 32 and indoor fan 42 may rotate at different rotational speeds, thereby generating different air flow rates. It may be desirable to operate fans 32, 42 at less than their maximum rated speed to ensure safe and proper operation of refrigeration loop 48 at less than its maximum rated speed, e.g., to reduce noise when full speed operation is not needed. In addition, according to alternative embodiments, fans 32, 42 may be operated to urge make-up air into the room.

According to the illustrated embodiment, indoor fan 42 may operate as an evaporator fan in refrigeration loop 48 to encourage the flow of air through indoor heat exchanger 40. Accordingly, indoor fan 42 may be positioned downstream of indoor heat exchanger 40 along the flow direction of indoor air and downstream of heating unit 44. Alternatively, indoor fan 42 may be positioned upstream of indoor heat exchanger 40 along the flow direction of indoor air and may operate to push air through indoor heat exchanger 40.

Heating unit 44 in exemplary embodiments includes one or more heater banks 60. Each heater bank 60 may be operated as desired to produce heat. In some embodiments as shown, three heater banks 60 may be utilized. Alternatively, however, any suitable number of heater banks 60 may be utilized. Each heater bank 60 may further include at least one heater coil or coil pass 62, such as in exemplary embodiments two heater coils or coil passes 62. Alternatively, other suitable heating elements may be utilized.

The operation of air conditioner unit 10 including compressor 34 (and thus refrigeration loop 48 generally) indoor fan 42, outdoor fan 32, heating unit 44, expansion device 50, and other components of refrigeration loop 48 may be controlled by a processing device such as a controller 64. Controller 64 may be in communication (via for example a suitable wired or wireless connection) to such components of the air conditioner unit 10. Controller 64 may include a memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of unit 10. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor.

Unit 10 may additionally include a control panel 66 and one or more user inputs 68, which may be included in control panel 66. The user inputs 68 may be in communication with the controller 64. A user of the unit 10 may interact with the user inputs 68 to operate the unit 10, and user commands may be transmitted between the user inputs 68 and controller 64 to facilitate operation of the unit 10 based on such user commands. A display 70 may additionally be provided in the control panel 66, and may be in communication with the controller 64. Display 70 may, for example be a touchscreen or other text-readable display screen, or alternatively may simply be a light that can be activated and deactivated as required to provide an indication of, for example, an event or setting for the unit 10.

Referring briefly to FIG. 4, a vent aperture 80 may be defined in bulkhead 46 for providing fluid communication between indoor portion 12 and outdoor portion 14. Vent aperture 80 may be utilized in an installed air conditioner unit 10 to allow outdoor air to flow into the room through the indoor portion 12. In this regard, in some cases it may be desirable to allow outside air (i.e., “make-up air”) to flow into the room in order, e.g., to meet government regulations, to compensate for negative pressure created within the room, etc. In this manner, according to an exemplary embodiment, make-up air may be provided into the room through vent aperture 80 when desired.

As shown in FIG. 5, a vent door 82 may be pivotally mounted to the bulkhead 46 proximate to vent aperture 80 to open and close vent aperture 80. More specifically, as illustrated, vent door 82 is pivotally mounted to the indoor facing surface of indoor portion 12. Vent door 82 may be configured to pivot between a first, closed position where vent door 82 prevents air from flowing between outdoor portion 14 and indoor portion 12, and a second, open position where vent door 82 is in an open position (as shown in FIG. 5) and allows make-up air to flow into the room. According to the illustrated embodiment vent door 82 may be pivoted between the open and closed position by an electric motor 84 controlled by controller 64, or by any other suitable method.

In some cases, it may be desirable to treat or condition make-up air flowing through vent aperture 80 prior to blowing it into the room. For example, outdoor air which has a relatively high humidity level may require treating before passing into the room. In addition, if the outdoor air is cool, it may be desirable to heat the air before blowing it into the room. Therefore, according to an exemplary embodiment of the present subject matter, unit 10 may further include an auxiliary sealed system that is positioned over vent aperture 80 for conditioning make-up air. The auxiliary sealed system may be a miniature sealed system that acts similar to refrigeration loop 48, but conditions only the air flowing through vent aperture 80. According to alternative embodiments, such as that described herein, make-up air may be urged through vent aperture 80 without the assistance of an auxiliary sealed system. Instead, make-up air is urged through vent aperture 80 may be conditioned at least in part by refrigeration loop 48, e.g., by passing through indoor heat exchanger 40. Additionally, the make-up air may be conditioned immediately upon entrance through vent aperture 80 or sequentially after combining with the air stream induced through indoor heat exchanger 40.

Referring now to FIG. 6, a fan assembly 100 will be described according to an exemplary embodiment of the present subject matter. According to the illustrated embodiment, fan assembly 100 is generally configured for urging the flow of makeup air through vent aperture 80 and into a conditioned room without the assistance of an auxiliary sealed system. However, it should be appreciated that fan assembly 100 could be used in conjunction with a make-up air module including an auxiliary sealed system for conditioning the flow of make-up air. As illustrated, fan assembly 100 includes an auxiliary fan 102 for urging a flow of make-up air through a fan duct 104 and into indoor portion 12 through vent aperture 80.

According to the illustrated embodiment, auxiliary fan 102 is an axial fan positioned at an inlet of fan duct 104, e.g., upstream from vent aperture 80. However, it should be appreciated that any other suitable number, type, and configuration of fan or blower could be used to urge a flow of makeup air according to alternative embodiments. In addition, auxiliary fan 102 may be positioned in any other suitable location within air conditioner unit 10 and auxiliary fan 102 may be positioned at any other suitable location within or in fluid communication with fan duct 104. The embodiments described herein are only exemplary and are not intended to limit the scope present subject matter.

Referring now to FIG. 7, operation of unit 10 will be described according to an exemplary embodiment. More specifically, the operation of components within indoor portion 12 will be described during a cooling operation or cooling cycle of unit 10. To simplify discussion, the operation of auxiliary fan 102 for providing make-up air through vent aperture 80 will be omitted, e.g., as if vent door 82 were closed. Although a cooling cycle will be described, it should be further appreciated that indoor heat exchanger 40 and/or heating unit 44 be used to heat indoor air according to alternative embodiments. Moreover, although operation of unit 10 is described below for the exemplary packaged terminal air conditioner unit, it should be further appreciated that aspects the present subject matter may be used in any other suitable air conditioner unit, such as a heat pump or split unit system.

As illustrated, room front 24 of unit 10 generally defines an intake vent 110 and a discharge vent 112 for use in circulating a flow of air (indicated by arrows 114) throughout a room. In this regard, indoor fan 42 is generally configured for drawing in air 114 through intake vent 110 and urging the flow of air through indoor heat exchanger 40 before discharging the air 114 out of discharge vent 112. According to the illustrated embodiment, intake vent 110 is positioned proximate a bottom of unit 10 and discharge vent 112 is positioned proximate a top of unit 10. However, it should be appreciated that according to alternative embodiments, intake vent 110 and discharge vent 112 may have any other suitable size, shape, position, or configuration.

During a cooling cycle, refrigeration loop 48 is generally configured for urging cold refrigerant through indoor heat exchanger 40 in order to lower the temperature of the flow of air 114 before discharging it back into the room. Specifically, during a cooling operation, controller 64 may be provided with a target temperature, e.g., as set by a user for the desired room temperature. In general, components of refrigeration loop 48, outdoor fan 32, indoor fan 42, and other components of unit 10 operate to continuously cool the flow of air.

In order to facilitate operation of refrigeration loop 48 and other components of unit 10, unit 10 may include a variety of sensors for detecting conditions internal and external to the unit 10. These conditions can be fed to controller 64 which may make decisions regarding operation of unit 10 to rectify undesirable conditions or to otherwise condition the flow of air 114 into the room. For example, as best illustrated in FIG. 7, unit 10 may include an indoor temperature sensor 120 which is positioned and configured for measuring the indoor temperature within the room. In this manner, unit 10 may be used to regulate the flow of air 114 into the room until the measured indoor temperature reaches the desired target temperature.

Now that the construction of air conditioner unit 10 and the configuration of controller 64 according to exemplary embodiments have been presented, an exemplary method 200 of operating a packaged terminal air conditioner unit will be described. Although the discussion below refers to the exemplary method 200 of operating air conditioner unit 10, one skilled in the art will appreciate that the exemplary method 200 is applicable to the operation of a variety of other air conditioning appliances. In exemplary embodiments, the various method steps as disclosed herein may be performed by controller 64 or a separate, dedicated controller.

Referring now to FIG. 8, method 200 includes, at step 210, receiving a command to enter a quiet operating mode of an air conditioner unit. In this regard, continuing the example from above, air conditioner unit 10 may be programmed to operate in a normal operating mode and a quiet operating mode. During the normal operating mode, the various components of unit 10 may operate under standard parameters that place an emphasis on quick temperature response. By contrast, in the quiet operating mode, air conditioner unit 10 may operate on an alternative set of operating parameters that seek to provide suitable temperature response while placing increased emphasis on improving energy efficiency, reducing noise, and/or optimizing room comfort.

Although the operating method 200 is described herein as being performed during a quiet operating mode, it should be appreciated that according to alternative embodiments, the method steps described herein may be performed in any other suitable operating mode, such as the normal operating mode. As such, according to an exemplary embodiment, placing unit 10 into the quiet operating mode is not necessary for performing the remaining steps of method 210. Indeed, it should be appreciated that the combination and order of method steps described herein are only exemplary and are not intended to limit the scope of the present subject matter in any manner.

According to exemplary embodiments, step 220 includes obtaining an indoor temperature using an indoor temperature sensor of the air conditioner unit. In this regard, for example, the indoor temperature may be obtained using any suitable temperature sensor positioned at any suitable location within or around the room being conditioned. This indoor temperature is generally used to facilitate operation air conditioner unit 10, e.g., to make informed decisions as to when and how the working components of unit 10 should operate. According to the exemplary embodiment, indoor temperature sensor 120 may be used to continuously or periodically monitor the indoor temperature to facilitate operation of unit 10 and the performance of method 200.

Step 230 includes operating a variable speed compressor, an indoor fan, and an outdoor fan of the air conditioner unit at a first capacity level to adjust the indoor temperature. For example, according to an exemplary embodiment, a user may program unit 10 to achieve a desired or target temperature, e.g., the desired room temperature. Step 230 generally includes operating these components and/or other components of air conditioner unit 10 to drive the indoor temperature toward the target temperature or to otherwise minimize a difference between the indoor temperature and the target temperature.

As used herein, the terms “capacity level” and the like are generally intended to refer to the operating capacity or intensity of each respective component of air conditioner unit 10. In general, these capacity levels vary among each component, but are generally complementary to each other. Thus, for example, if the overall unit is intended to be performing at 30% capacity level, each of compressor 34, indoor fan 42, and outdoor fan 32 may be operating at 30% of their rated capacity. Thus, for example, if a full rated capacity of compressor 34 is 5000 RPM and the capacity level is 40%, compressor 34 may target operation at 2000 RPM. Although capacity level may be consistent across compressor 34, indoor fan 42, and outdoor fan 32, it should be appreciated that this is not a requirement. Thus, if the unit capacity level is 30%, compressor 34 may be operating at 35% rated speed, while indoor fan 42 and outdoor fan 32 operate at 25% rated speed, for example.

As noted above, step 230 includes operation at a first capacity level, which may be interchangeably referred to herein as a starting capacity level or a low capacity level. In this regard, system operation begins at the low capacity level to see if demand on the air conditioner unit may be met at that capacity level while conserving energy, improving efficiency, and/or reducing noise. According to exemplary embodiments, the first capacity level comprises operation of each of compressor 34, indoor fan 42, and outdoor fan 32 at or below 40%, at or below 30%, at or below 25%, at or below 20%, or at or below 10%, of a respective rated capacity of each component.

Notably, while energy efficiency and reduced noise are desirable, it is also important that unit 10 is able to meet the conditioning needs for the room. As such, method 200 may include checks to ensure that unit 10 is cooling at a suitable rate. Specifically, step 240 includes determining that a rate of change of the indoor temperature is below a predetermined rate threshold. In general, the predetermined rate threshold may be any suitable rate of temperature change (e.g., in degrees Fahrenheit per time interval) that is deemed suitable for unit performance. It should be appreciated that this predetermined rate threshold may be determined in any suitable manner. For example, the predetermined rate threshold may be set by the user, programmed by the manufacturer, calculated by controller 64 based on room conditions, etc.

It should be appreciated that the rate of change of the indoor temperature may be monitored in any suitable manner. For example, such monitoring may include obtaining temperature measurements at specific time intervals and checking to see whether the indoor temperature has changed by a specific temperature differential within that time interval. Thus, if the predetermined time interval has passed since the system began operating at a first capacity level and the indoor temperature has not changed by at least a predetermined temperature differential within that time interval, the unit may determine that the rate of change is below the predetermined rate threshold. It should be appreciated that the predetermined time interval may be any suitable period of time, such as between about 5 seconds and 30 minutes, between about 30 seconds and 20 minutes, between about 1 minute and 10 minutes, or about five minutes.

In the event the rate of change of indoor temperature is below the predetermined rate threshold, it may be desirable to increase the capacity level of unit 10 in order to more appropriately meet the cooling or heating demands in a particular application or otherwise expedite the adjustment of the indoor temperature toward the target temperature. Thus, according to exemplary embodiments, step 250 includes operating the variable speed compressor, the indoor fan, and the outdoor fan at a second capacity level. According to exemplary embodiments, the second capacity level is an elevated capacity level, e.g., higher than the first capacity level and intended to heat or cool the room more quickly. According to exemplary embodiments, the second capacity level comprises operation of each of compressor 34, indoor fan 42, and outdoor fan 32 above the corresponding first capacity levels, e.g., such as above 20%, above 30%, above 35%, above 50%, or above 70%, of a respective rated capacity of each component.

As described above, method 200 includes steps for increasing the capacity level of unit 10 and its associated components in the event the cooling or heating capacity is not suitable (e.g., does not meet the predetermined rate threshold for temperature change). Although a single adjustment is described, e.g., from the first or low capacity to the second or high capacity operation, it should be appreciated that any suitable capacity intervals or increments may be used while remaining within the scope of the present subject matter. For example, unit 10 may have ten capacity levels corresponding to 10% performance capacity and in 10% increments all the way up to 100% performance capacity. In this manner, unit 10 may begin at a low level of operation and may slowly increment the system performance or capacity to meet the conditioning demands of a particular room while ensuring that the indoor temperature does not overshoot the target temperature or a range surrounding the target temperature. As a result, energy efficiency of unit 10 may be increased noise and power consumption are decreased.

In addition, although steps 240 and 250 are directed to increasing capacity when the conditioning needs of a room are not met, it should be appreciated that unit 10 may be programmed to maintain operation at a specific capacity level in the event the conditioning needs are being met. In this regard, method 200 may further include determining that a rate of change of the indoor temperature is above a predetermined rate threshold, and in response to such determination, maintaining operation of the variable speed compressor the indoor fan in the outdoor fan at the current capacity level, e.g., such as the first capacity level. In addition, method 200 may include steps of determining that the indoor temperature has reached the target room temperature or is within a predetermined narrow range surrounding the target room temperature (e.g., such as plus or minus 1 degree Fahrenheit, 2 degrees Fahrenheit, 3 degrees Fahrenheit, etc.). In such event, method 200 may include stopping the operation of the variable speed compressor, the indoor fan, and the outdoor fan.

Referring now briefly to FIG. 9, an exemplary flow diagram of a quiet mode of operation for an air conditioner unit have a variable speed compressor and indoor/outdoor fans will be described according to an exemplary embodiment of the present subject matter. In general, steps of method 300 may correspond with or be interchangeable with steps of method 200. In addition, it should be appreciated that the method steps described herein are only exemplary and are not intended to limit the scope of the present subject matter in any manner.

As shown, step 302 includes placing the air conditioner unit into the quiet mode. It should be appreciated that a user may place unit 10 in a quiet mode in any suitable manner, such as via a user interface or control panel 66, through a remote device such as a mobile phone running a software application, or in any other suitable manner. Step 304 includes operating unit 10 at a lowest possible setting for a set period of time, e.g., such as between about 1 and 20 minutes. In this regard, the system controller may operate the compressor, the indoor fan, the outdoor fan, and other system components at a first or lowest rated capacity level.

Step 306 may include determining whether the indoor temperature has changed by a certain threshold temperature differential (e.g., such as X degrees) since the prior temperature sampling. If the indoor temperature has not changed by the predetermined amount, step 308 may include increasing the capacity level of the unit to increase the rate of temperature change. In this regard, the capacity or speeds of the compressor, the indoor fan, and the outdoor fan may be increased by a predetermined amount or elevated to a predetermined level for a set period of time. This process of increasing the capacity level of the air conditioner unit may continue until the rate of change of the indoor temperature reaches the desired threshold.

If at step 306 it is determined that the indoor temperature is changing by the desired rate, step 312 may include maintaining system operation at that level. In this regard, for example, the unit may continue operation at the current speeds for a predetermined amount of time. Step 314 may include determining whether the indoor set temperature or target temperature has been reached. If the indoor temperature has not reached a target temperature method 300 may proceed back to step 306 to ensure that the rate of temperature change still meets the desired threshold. If step 314 results in a determination that the indoor temperature has reached the target temperature, system operation may be stopped at step 316. In this regard, the compressor, the indoor fan, and the outdoor fan may be turned off or set to a minimal operating speed to maintain the indoor temperature at the target temperature.

FIGS. 8 and 9 depict steps performed in a particular order for purposes of illustration and discussion. Those of ordinary skill in the art, using the disclosures provided herein, will understand that the steps of any of the methods discussed herein can be adapted, rearranged, expanded, omitted, or modified in various ways without deviating from the scope of the present disclosure. Moreover, although aspects of method 200 and method 300 are explained using unit 10 as an example, it should be appreciated that this method may be applied to operate any suitable air conditioner unit.

Notably, conventional room air conditioners have been manufactured with single speed compressors. However, the market for room air conditioners has begun to place increased emphasis on improved energy efficiency, lower noise, and improved temperature regulation. Aspects of the present subject matter are directed toward the use and implementation of inverter compressor technology to address some of these concerns. Specifically, the presently disclosed methods may drive the compressor and heat exchanger fans to get the most noise and energy efficiency benefits. For example, it may be desirable to operate the air conditioner at the lowest possible capacity to maximize the benefits, but due to environmental heat loads from the weather and from the quality of the building structure, the unit may also be able to accommodate the need for more aggressive cooling capacities when needed. The described method may achieve this by comparing the rate of change of the air temperature in the room at given time intervals to determine the optimum operating points for the compressor and the fan.

In this regard, for example, software programmed into controller 64 may make comparisons between a set temperature and a room temperature at pre-programmed time intervals. If the difference between the set temperature and the room temperature is relatively small and getting smaller by a predetermined threshold within a given time interval, the software may determine there is no need to increase the capacity or fan speed. If the software determines that these conditions are not being met, then the capacity and fan speeds may be increased. The maximum noise and energy efficiency may be realized when the unit operates at the lowest capacity and fan speed over a longer time period as compared to higher capacity and higher fan speed for a shorter time. Overall room comfort can be maximized as well because the unit may be dehumidifying the air as well being constantly adding cooler than room temperature air to the space.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

What is claimed is:
 1. An air conditioner unit comprising: a refrigeration loop comprising an outdoor heat exchanger and an indoor heat exchanger; a variable speed compressor operably coupled to the refrigeration loop and being configured for urging a flow of refrigerant through the outdoor heat exchanger and the indoor heat exchanger; an indoor fan configured for urging a flow of indoor air through the indoor heat exchanger; an outdoor fan configured for urging a flow of outdoor air through the outdoor heat exchanger; an indoor temperature sensor; and a controller operably coupled to the variable speed compressor, the indoor fan, the outdoor fan, and the indoor temperature sensor, the controller being configured to: obtain an indoor temperature using the indoor temperature sensor; operate the variable speed compressor, the indoor fan, and the outdoor fan at a first capacity level to adjust the indoor temperature; determine that a rate of change of the indoor temperature is below a predetermined rate threshold; and operate the variable speed compressor, the indoor fan, and the outdoor fan at a second capacity level.
 2. The air conditioner unit of claim 1, wherein the controller is further configured to: obtain a target room temperature; operate the variable speed compressor, the indoor fan, and the outdoor fan to minimize a difference between the indoor temperature and the target room temperature.
 3. The air conditioner unit of claim 2, wherein the controller is further configured to: determine that the indoor temperature is within 2 degrees Fahrenheit above or below the target room temperature; and stop operation of the variable speed compressor, the indoor fan, and the outdoor fan.
 4. The air conditioner unit of claim 1, wherein the controller is further configured to: determine that the rate of change of the indoor temperature is above the predetermined rate threshold; and maintain operation of the variable speed compressor, the indoor fan, and the outdoor fan at the first capacity level.
 5. The air conditioner unit of claim 1, wherein the controller is further configured to: operate the variable speed compressor, the indoor fan, and the outdoor fan at the second capacity level to adjust the indoor temperature; determine that the rate of change of the indoor temperature is below the predetermined rate threshold; and operate the variable speed compressor, the indoor fan, and the outdoor fan at a third capacity level.
 6. The air conditioner unit of claim 1, wherein the controller is further configured to: receive a command to enter a quiet operating mode before operating the variable speed compressor, the indoor fan, and the outdoor fan at the first capacity level.
 7. The air conditioner unit of claim 1, wherein the first capacity level comprises operation of each of the variable speed compressor, the indoor fan, and the outdoor fan at or below 25% of a respective rated capacity.
 8. The air conditioner unit of claim 1, wherein the second capacity level comprises operation of each of the variable speed compressor, the indoor fan, and the outdoor fan at or above 35% of a respective rated capacity.
 9. The air conditioner unit of claim 1, wherein determining that the rate of change of the indoor temperature is below the predetermined rate threshold comprises: determining that a predetermined time interval has passed since the variable speed compressor, the indoor fan, and the outdoor fan began operating at the first capacity level; and determining that the indoor temperature has not changed by at least a predetermined temperature differential within the predetermined time interval.
 10. The air conditioner unit of claim 9, wherein the predetermined time interval is between about 1 minutes and 20 minutes.
 11. The air conditioner unit of claim 1, wherein the variable speed compressor is an inverter compressor.
 12. A method of operating an air conditioner unit, the air conditioning unit comprising a refrigeration loop, a variable speed compressor, an indoor fan, an outdoor fan, and an indoor temperature sensor, the method comprising: obtaining an indoor temperature using the indoor temperature sensor; operating the variable speed compressor, the indoor fan, and the outdoor fan at a first capacity level to adjust the indoor temperature; determining that a rate of change of the indoor temperature is below a predetermined rate threshold; and operating the variable speed compressor, the indoor fan, and the outdoor fan at a second capacity level.
 13. The method of claim 12, further comprising: obtaining a target room temperature; operating the variable speed compressor, the indoor fan, and the outdoor fan to minimize a difference between the indoor temperature and the target room temperature.
 14. The method of claim 13, further comprising: determining that the indoor temperature is within 2 degrees Fahrenheit above or below the target room temperature; and stopping operation of the variable speed compressor, the indoor fan, and the outdoor fan.
 15. The method of claim 12, further comprising: determining that the rate of change of the indoor temperature is above the predetermined rate threshold; and maintaining operation of the variable speed compressor, the indoor fan, and the outdoor fan at the first capacity level.
 16. The method of claim 12, further comprising: operating the variable speed compressor, the indoor fan, and the outdoor fan at the second capacity level to adjust the indoor temperature; determining that the rate of change of the indoor temperature is below the predetermined rate threshold; and operating the variable speed compressor, the indoor fan, and the outdoor fan at a third capacity level.
 17. The method of claim 12, further comprising: receiving a command to enter a quiet operating mode before operating the variable speed compressor, the indoor fan, and the outdoor fan at the first capacity level.
 18. The method of claim 12, wherein the first capacity level comprises operation of each of the variable speed compressor, the indoor fan, and the outdoor fan at or below 25% of a respective rated capacity.
 19. The method of claim 12, wherein the second capacity level comprises operation of each of the variable speed compressor, the indoor fan, and the outdoor fan at or above 35% of a respective rated capacity.
 20. The method of claim 12, wherein determining that the rate of change of the indoor temperature is below the predetermined rate threshold comprises: determining that a predetermined time interval has passed since the variable speed compressor, the indoor fan, and the outdoor fan began operating at the first capacity level; and determining that the indoor temperature has not changed by at least a predetermined temperature differential within the predetermined time interval. 